process continues after app closed on one pc

I have an app written in dot net and when the app is exited correctly its exe process continues to run, I start and close this app several times and I then have several instances of the exe running in the processes?
So far this only seems to be happening on only one of the 10 PC's we have tried it on?
Anyone got any suggestions why this could be the case?
Win 7 64 bit
thanks

Featured Post

Enroll today in this bundle of courses to gain experience in the logistics of pen testing, Linux fundamentals, vulnerability assessments, detecting live systems, and more! This series, valued at $3,000, is free for Premium members, Team Accounts, and Qualified Experts.